Abstract This application proposes to contribute to the harmonization of law enforcement practices and public health goals to combat rising morbidity and mortality rates associated with opioid-related overdose (OD). Police departments around the U.S. are increasingly making the OD reversal drug, naloxone, available to their officers. This intervention has the potential to greatly improve emergency response after an OD. The proportion of precincts mandating that officers carry naloxone remains small, however, and barriers remain that make adoption of these first-responder programs problematic. Lawsuits from police unions contesting naloxone- related mandates and occupational safety concerns, including the potential for needle stick injuries (HIV/HCV risk) and incidental contact with fentanyl-class substances, constitute barriers, as do stigma and concerns about legal jeopardy. The study team proposes to equip police with best-practices for minimizing workplace harms related to encounters with PWUO/PWID and the legal and practical knowledge to respond confidently to an OD without fear of legal jeopardy as well as reduce health risks to PWUOs and PWIDs associated with law enforcement. More than 10,000 law enforcement officers in Pennsylvania (roughly one third of all PA officers) have already received naloxone and OD response training from GetNaloxoneNow.org (GNN), a web-based intervention. With the support of county departments of health, harm reduction agencies, law enforcement, and district attorneys, the team proposes to adapt extant interventions for police to create an online training module aimed at reducing barriers to police engagement in OD response. Using a mixed-method design, organized around a pragmatic trial design, the study will achieve the following objectives:1) Adapt an occupational risk reduction (ORR) curriculum to add to a web-based OD response and naloxone training platform (GNN); 2) Describe naloxone use patterns, OD response experiences, and attitudes related to illicit opioid use among a sample (N = 300) of police officers in PA trained via the GNN platform; 3) Evaluate the relative effectiveness of ORR + GNN, compared with GNN-only, with respect to the following outcomes: a) rates of carrying naloxone while on/off-duty; b) rates of OD response in which naloxone is/isn't administered; c) numbers of referrals to treatment; d) numbers of syringes confiscated; and e) rates of information sharing with OD survivors and others. Mediators and moderators of efficacy will also be analyzed. 4) Document the range of psychosocial mechanisms underlying participant OD response engagement post-intervention. This study aims to remove barriers to life-saving police engagement with PWUO/PWID by focusing both on the safety of law enforcement and evidence-based and best-practices for working with persons at risk of an opioid OD. The study also will provide empirical evaluation of the diffusion of naloxone-based response among law enforcement.